AN EXCESS-FLOW SAFETY SHUT-OFF DEVICE

Abstract: A fluid flow safety device comprising a body having an inlet end for connection to a fluid supply and an inlet passageway which leads to a selective fluid flow sensor chamber and located at the outlet end of the said sensor chamber is a sealing means which encircles the outlet orifice and this outlet orifice is of smaller cross section than that of the sensor chamber, said outlet orifice leading from the sensor chamber into a pressure chamber within the body. Between the inlet end of the sensor chamber and the sealing means is a tapered section, wherein the bore of the sensor chamber decreases in diameter as it nears the sealing means. A movable plug which is positioned within the selective fluid flow sensor chamber can move between the inlet passageway end stop of the sensor chamber and the outlet orifice, and the movable plug is of greater diameter than the sensor chamber outlet orifice and is able to form a seal with the sealing means. This seal can occur when the flow of fluid through the sensor chamber is above a predetermined value. Within the pressure chamber is a movable piston which makes a sliding and sealing contact with it and whose sliding movement from a rest position increases or decreases the volume of the said pressure chamber. A passageway leading from the pressure chamber to an outlet aperture is connectable to further fluid transport mechanisms. One embodiment includes an indicator mark on the movable piston which is visible only when the pressure in the pressure chamber is above a predetermined value and a movement of the movable piston from a rest position fully towards the sensor chamber will deny a seal to be made between the movable plug and the sealing means. In the preferred embodiment, the movable piston is the primary valve mechanism which forms a seal between the inlet and outlet passageways. A sensor chamber shield encircles the sensor chamber by forming, defining and separating the internal length of the sensor chamber passageway from that of the inlet or any other passageway.

Description: AN EXCESS-FLOW SAFETY SHUT-OFF DEVICE This invention relates to the provision of a user friendly, inexpensive and simplified excess-flow safety shut-off device for the control of hazardous, expensive or precious fluids. While this invention was originally developed to provide additional protection for LP gas users, it has wider applications than that of just gas cylinder operations. For simplicity however, it will be described with reference to LP gas applications in this text. This safety device particularly addresses the requirement to contain flammable gases in the cylinder when a variety of potentially hazardous situations occur. For particular applications, it also helps ensure the correct orientation of the gas cylinder so that only fuel in its gaseous state can proceed from the cylinder and through the device. LP gas is an efficient, effective and economical fuel source which, when treated correctly, is completely safe. However time, wear and tear, customer misuse and equipment failures can produce a variety of unsafe operational conditions which this invention specifically seeks to address. BACKGROUND ART Previous inventions relating to safety shut-off devices for LP, butane, coal or natural gas, reference the different methods of housing, locating or resetting the various shut-off valve mechanisms which terminate the fluid flow when certain operational conditions are encountered. Many of the previous inventions, which range from the over simplified to the complex, only provide an adequate level of protection in a very limited number of operational states, are not consistent regarding their shut-off flow rates and often contain additional components which .are either not required, which require regular servicing, which can be confusing, which do not enhance the safety functioning of the shut-off device or whose presence only adds to the cost of manufacture which, in turn, increases the retail price of the unit. Previous devices which include gas pressure gauges often cause operators to believe that they now have an indication of the gas contents of the cylinder when, in fact, all they have is an indication of the actual gas pressure of the supply line at that moment. When LP gas converts from its liquid to its gaseous state, it expands some two hundred and seventy times in volume. When contained within a sealed cylinder, Boyle's Law can be used to help show the ratio of gas to fluid and the pressure at various temperatures. Therefore, a very small quantity of fluid LP gas within the cylinder can register a pressure of around one hundred pounds per square inch, which is within the bounds of the normal supply pressure and which is the reading that a full cylinder will register, even though the cylinder is almost empty. When this normal pressure is observed, some operators therefore expect that the cylinder contains an adequate supply of gas for their immediate needs. When this is found to be not the case, the safety device is often considered to be somehow faulty and is then removed from the system, thus eliminating whatever level of safety shut-off protection which was being provided by that device. Some of the previous devices do not shut-off if the gas cylinder falls onto its side or, if a less than half full cylinder is being operated while lying on its side. The orientation of the gas cylinder should effect the shut-off device as, in some instances, this is the only method of detecting that an unsafe condition exists and prevents it from then becoming life threatening. For example, a mantle lantern mounted onto a small portable gas cylinder in a camping type situation should not remain operational when lying on its side. Another problem which inflicts many of the previous inventions is that they are inconsistent with regard to their maximum flow rates. These flow rates should be at their maximum when the cylinder is in its correct orientation and must then decrease as the cylinder deviates from that orientation regardless through which axes the deviation is occurring. Many of the previous inventions are sensitive to one style of deviation and tests have shown that, instead of registering reduced fluid flows when placed in these positions, they actually register substantially increased flows. Many of the disadvantages of the previous invention include their methods of construction. Those that contain user serviceable components, adjustment mechanisms or those which can be dissembled, all lend themselves to the effects of incorrect reassembly or tampering. This can seriously effect their efficiency of operation. DISCLOSURE OF THE INVENTION It is therefore an object of the present invention to overcome the abovementioned problems in a reliable and inexpensive manner. According to one form of the present invention there is provided a fluid flow safety device comprising; a body, having an inlet for connection to a fluid supply, an inlet passageway leading to a selective fluid flow sensor chamber, and located at the outlet end of the said sensor chamber is a sealing means which encircles an outlet orifice and this outlet orifice is of smaller cross section than that of the sensor chamber, said outlet orifice leading from the sensor chamber into a pressure chamber within the body; a movable piston which makes a sliding and sealing contact with the pressure chamber, and whose sliding movement from a rest position increases or decreases the volume of the said pressure chamber and a plunger is incorporated into the base of the movable piston and an indicator mark on the movable piston is visible when the pressure in the pressure chamber is above a predetermined valve; a passageway extending from the pressure chamber to an outlet aperture which is connectable to further fluid transport mechanisms; and a movable plug which is positioned within the selective fluid flow sensor chamber and can move between the inlet passageway end stop of the sensor chamber and the outlet orifice, and the movable plug is of greater diameter than the sensor chamber outlet orifice and is able to form a seal with the sealing means and the diameter of the movable plug in relation to the internal diameter of the sensor chamber allows a predetermined quantity of fluid to flow to the outlet orifice wherein an increase in the fluid flow above that predetermined quantity, draws the movable plug into a sealing contact with the sealing means at the outlet orifice. In another form of the present invention there is provided a fluid flow safety device comprising; a body, with an inlet assembly containing a fluid passageway which provides a mating connection to form a fluid tight seal between the body inlet orifice and is connectable to a fluid supply source and, has an inlet passageway leading to a selective fluid flow sensor chamber, and located at the outlet end of the said sensor chamber is a sealing means which encircles an outlet orifice and this outlet orifice is of smaller cross section than, that of the sensor chamber, said outlet orifice leading from the sensor chamber into a pressure chamber within the body; a guide for the movable piston is located onto the body to form part of the pressure chamber and has i s axis is aligned to the axis of the outlet orifice; a movable piston which makes a sliding and sealing contact with the guide, and whose sliding movement increases or decreases the volume of the pressure chamber and a plunger is incorporated into the base of the movable piston and an indicator mark on the movable piston is visible when the pressure in the pressure chamber is above a predetermined valve; a passageway extending from the pressure chamber to an outlet aperture which is connectable to further fluid transport mechanisms; and a movable plug which is positioned within the selective fluid flow sensor chamber and can move between the inlet passageway end stop of the sensor chamber and the outlet orifice, and the movable plug is of greater diameter than the sensor chamber outlet orifice and is able to form a seal with the sealing means and the diameter of the movable plug in relation to the internal diameter of the sensor chamber allows a predetermined quantity of fluid to flow to the outlet orifice wherein an increase in the fluid flow above that predetermined quantity, draws the movable plug into sealing contact with the sealing means at the outlet orifice. In another form of the present invention there is a fluid flow safety device comprising; an inlet assembly with a fluid passageway for connection to a fluid supply, a body having an inlet passageway leading to a selective fluid flow sensor chamber, and located at the outlet end of the of the said sensor chamber is a sealing means which encircles an outlet orifice and this outlet orifice is of smaller cross section than that of the sensor chamber, said outlet orifice leading from the sensor chamber to a pressure chamber within the body; a movable piston which makes a sliding and sealing contact within the pressure chamber, and whose central axis is aligned with the central axis of the sensor chamber and the opposite end of the movable piston to that which is located within the bounds of the sliding and sealing contact of the pressure chamber, experiences the effect of atmospheric pressure; a passageway extending from the pressure chamber to an outlet aperture which is connectable to further fluid transport mechanisms; a movable plug which is positioned within the selective fluid flow sensor chamber and is located between the inlet passageway and the outlet orifice, and the movable plug is of greater diameter than the sensor chamber outlet orifice and the diameter of the movable plug in relation to the internal diameter of the sensor chamber allows a predetermined quantity of fluid to flow to the outlet orifice wherein an increase in the fluid flow above that predetermined quantity, draws the movable plug into a sealing contact with the sealing means at the outlet orifice; and a separate shut-off mechanism to provide an independent control for terminating or initiating the fluid flow wherein part of the separate shut-off mechanism can be biased towards the closed position and can be held in the open state by a triggering system. In another form of the present invention there is provided a fluid flow safety device comprising; a body having an inlet end for connection to a fluid supply and an outlet end for connection to further fluid transport mechanisms, an inlet passageway leading to a valve orifice passageway which leads to a primary valve seat and primary valve pressure chamber which connects via the outlet passageway to the outlet end; a primary valve mechanism is located within the primary valve pressure chamber such that it can form a fluid tight seal between the inlet and the outlet passageways by engaging with the primary valve seat; a selective fluid flow sensor chamber and located at the outlet end of the said sensor chamber is a sealing means which encircles an outlet orifice and this outlet orifice is of smaller cross section than that of the sensor chamber said outlet orifice leading from the sensor chamber to the valve orifice; a sensor chamber shield which encircles the sensor chamber by forming, defining and separating the internal length of the sensor chamber passageway from that of the inlet or any other passageway; a movable plug which is positioned within the fluid flow sensor chamber and can move between the inlet passageway end of the sensor chamber and the outlet orifice and is able to form a seal with the sealing means; a safety valve passageway extends from the inlet passageway to a safety valve mechanism which has been designed to vent to the atmosphere that fluid from the safety valve passageway should the pressure in that passageway rise above a predetermined valve. In another form of the present invention there is a fluid flow safety shut-off mechanism comprising; an attaching guide housing which is connectable with a fluid flow safety device body, said attaching guide housing containing a central guide hole and a mating connection for a spindle mechanism; a movable piston which makes a sealing and sliding contact within the central guide hole in the attaching guide housing, said movable piston containing a cylindrical chamber and a valve plug; a reset plunger pin, one end of which makes a sliding, sealing contact within the cylindrical chamber while the other end is located within an oversized orifice in the centre of the valve plug; a spindle mechanism which makes a mating connection with the attaching guide housing and which, when rotated towards its closed position, urges the movable piston from the attaching guide housing and the said spindle contains a central guide hole which extends longitudinally through its central axis; a handle which combines with the spindle to transmit the rotational movement to the spindle; a reset shaft which, when moved to its reset position, engages with the reset plunger pin and extends it through the valve plug to its reset position; and an indicator mark is present on the reset shaft extension which is only visible when the reset shaft is in its fully extended position. BRIEF DESCRIPTIONS OF THE DRAWINGS As there are several different presentations for this invention they will now be described, by way of example only, with reference to the accompanying drawings wherein: figure 1 shows the operational and pressurized condition of one version of the vertical presentation of the fluid flow safety device while, figure 2 shows the shut-off condition of the same vertical version while, figure 3 shows the reset condition of the same vertical version while, figure 4 shows the operational and pressurized condition of one version of the horizontal presentation of the fluid flow safety device while, figure 5 shows the shut-off condition of the activation components of the same horizontal version while, figure 6 shows the reset condition of the activation components of the same horizontal version while, figure 7 shows the operational and pressurized condition of the version of the fluid flow safety device for mounting directly into the main outlet of the gas cylinder while, figure 8 shows the rest position of the fluid flow safety shut-off mechanism while, figure 9 shows the reset position of the fluid flow safety shut-off mechanism while, figure 10 shows the pressurized position of the fluid flow safety shut-off mechanism. In the drawings designated as figures 1, 2 and 3 there is shown a vertical version of a fluid flow safety device 1 which is connectable to a gas cylinder (not shown) at the inlet end 2 of the body 3. In the version shown in these figures the inlet assembly 4 is separate from, and connectable to the body 3. As this version is designed to have a metal inlet assembly and a plastic body, the 0-ring 5 provides a fluid tight seal between the two components. The upper periphery 6 of the inlet assembly is crimped into the groove 7 located on the lower portion of the body. This design seeks to substantially reduce the cost of manufacture while still meeting those regulatory requirements which demand a metal body for the containment of flammable gases. In this design, should the unit become engulfed in flames and the plastic components melt and loose the ability to contain the fluid, the excess flow will be contained within the metal inlet assembly as the movable plug forms a seal with the sealing means. However, it is envisaged that the inlet assembly and the body can be manufactured from the same material and this will in no way alter the intent of this invention. Contained within the inlet assembly is an inlet passageway 8 which leads to a selective fluid flow sensor chamber 9 and a sealing means 10 which encircles the outlet orifice 11 of the sensor chamber which leads to a pressure chamber 12 within the body. In these three drawings the sealing means is shown as an 0-ring which is held in place with a removable tapered sensor chamber passageway 13. A inlet passageway end stop 14 is firmly inserted into the end of the inlet passageway and, as it is highly resistant to being removed, renders the sensor chamber tamper proof. The inlet passageway end stop also locates the removable sensor chamber passageway in its correct position. It should be noted that the sealing means can also be a radius which matches the movable plug and can be machined into the end of the sensor chamber and the cylindrical walls of the sensor chamber can then be formed to resemble the profile of the internal passageway as shown by the removable tapered sensor chamber passageway. The inlet passageway end stop can have a tapered outlet 15 which combines with the movable plug 16 to provide a one way valve. Also, the inlet passageway, end stop can contain a filtering material within its passageway to help ensure that foreign material is excluded from the sensor chamber. The positioning of the movable plug within the sensor chamber herein defined by a larger diameter 17, a tapered section 18 and a smaller diameter 19 enhances the effects of Bernoulli's theorem on the movable plug in that as the movable plug is drawn towards the outlet orifice by the flow of the fluid, as the movable plug approaches the outlet orifice the pressure increases until the seal with the sealing means is achieved. Also, the tapered section allows for a much lower flow rate to move the movable plug to the sealing means when the unit is in a horizontal alignment. Thus, if the unit falls onto its side, it is very responsive to a quick shut-off. Within the pressure chamber of the body is movable piston 20 which has two circlip grooves 21 and 22, a passageway 23 and an extension 24 at the outlet end for connection to further fluid transport mechanisms. Between the two circlips 25 and 26 are two spacer rings 27 and 28 and between them are two 0-rings 29 and 30 and a shim 31. While two 0-rings are not essential, many of the regulatory authorities require a double seal between a pressure chamber and atmosphere. Between the circlip 26 and the further fluid transport mechanism is a spacing ring stop 32, a spring 33 and an inverted spacing ring stop 34. Within the step in the chamber walls 35 of the body is a circular internal push-on fastener 36 which, when in place, renders the top end of the unit virtually tamper proof. It should be noted that the inverted spacing ring stop and the internal push-on fastener could be replaced by a groove in the pressure chamber walls and a compression clip ring. There is a groove 37 in the extension of the movable piston which contains a indicator mark 38 which could be a green neoprene 0-ring. Mounted onto the base of the movable piston is a plunger 39 which has a passageway 40 which allows fluids to flow between the pressure chamber and the passageway 23. At the narrow passage 41 can be installed a one way valve should the need arise. In figure 1, the fluid flow safety device is shown in the condition that it will be in when it is passing pressurized fluid at a rate below the maximum predetermined flow rate for that unit. The movable plug is near the base of the sensor chamber and the pressure in the pressure chamber forces the movable piston into the position shown and the volume of the pressure chamber increases to its maximum. This is achieved by 0-ring 29 pressing the shim 31 onto the 0-ring 30 which presses the spacer ring 28 which presses the circlip 26 onto the spacing ring stop 32 whose limit of travel is reached when the spring 33 is fully compressed against the inverted spacing ring stop 34 which is resting upon the circular internal push-on fastener 36. In figure 2, the fluid flow safety device is shown in the condition that it will be in when an emergency shut-off has occurred. The movable plug 16 has been forced onto the sealing means 10 at the end of the sensor chamber 9 at the outlet orifice end. The circular internal push-on fastener 36 which is immovable within the chamber walls of the body, is anchoring the inverted spacing ring stop 34 which has the upper end of the spring 33 pressing against it. The other end of the spring has forced the spacing ring stop 32 to come to rest against the step in the bore of the pressure chamber 42. The action of the still tensioned spring which is held between the circular internal push-on fastener and the step in the bore of the pressure chamber holds the movable piston between the inverted spacing ring stop pressing against the movable piston's extension at 43 and the spacing ring stop pressing onto the circlip 27. When there are no external forces acting upon the movable piston 20, it returns to this position. The plunger 39 does not touch the movable plug. The indicator mark 38 is no longer visible and the volume of the pressure chamber returns to its rest volume. In figure 3, the fluid flow safety device is shown in the condition that it will be in when it is being reset. The reset occurs when an external force moves the movable piston into the position as shown. The extension of the movable piston at 43 moves the inverted spacing ring stop 34 away from the circular internal push-on fastener 36 and compresses the spring 33 against the spacing ring stop 32 which can not move as it is held in place by the step in the bore of the pressure chamber 42. While held in this position, the volume of the pressure chamber decreases to, or near, its minimum. The plunger 39 has moved the movable plug 16 away from the sealing means 10 and this action allows the pressure chamber to become pressurized and, providing a sufficient pressure is obtained, returns the device to the condition as shown in figure 1. In the drawings designated as figures 4, 5 and 6 there is shown a horizontal version of a fluid flow safety device 44 which is connectable to a gas cylinder (not shown) at the inlet assembly 45 which, in this case has a POL type mating connection, and connects with the body 46. In the version shown in these figures the inlet assembly 45 is separate from, and connectable to the body. As this version is not intended to be taken apart, an industrial adhesive is used to bond the inlet assembly to the body. Contained within the inlet assembly is an inlet passageway 48 which leads to a selective fluid flow sensor chamber 49 and a sealing means 50 which encircles the outlet orifice 51 of the sensor chamber which leads to a pressure chamber.52 within the body. In these three drawings the sealing means is shown as an 0-ring which is held in place with a removable tapered sensor chamber passageway 53. A inlet passageway end stop 47 is pin which is firmly inserted into the body. The inlet assembly can contain a filtering material within its passageway to help ensure that foreign material is excluded from the sensor chamber. The positioning of the movable plug 56 within the sensor chamber herein defined by a larger diameter 57, a tapered section 58 and a smaller diameter 59 enhances the effects of Bernoulli's theorem on the movable plug in that as the movable plug is drawn towards the outlet orifice by the flow of the fluid, as the movable plug approaches the outlet orifice the pressure increases until the seal with the sealing means is achieved. Also, the tapered section allows for a much lower flow rate to move the movable plug to the sealing means when the orientation of the sensor chamber is in a horizontal alignment. Thus, if the unit falls * onto its side, it is very responsive to a quick shut-off. The tapered sensor chamber passageway 53 is removable from the body. In order to form a fluid tight seal between the sensor chamber and the pressure chamber an 0-ring 54 surrounds the tapered sensor chamber passageway and forms a seal between the body and the removable outlet orifice 55 of the sensor chamber. The removable outlet orifice passageway holds the tapered sensor chamber in place and, in turn, it is held in place by the vented plug 201 which connects with the guide 202 which attaches to the body. A passageway 203 leads to the outlet end for connection to further fluid transport mechanisms. The guide forms part of the pressure chamber and, within the guide hole 206, resides the movable piston 60 which has a circlip groove 61 and a circlip 65 located ' at its lower end. An angled stop 64, a spring 63 and spacer ring 204 are located between the circlip and the step in the piston at 205. A step in the guide hole's chamber walls 207 limits the outward travel of the spacer ring. The angled stop is able to travel between the vented plug and the step in the guide hole's chamber walls at 208. There is a groove 67 in the extension of the movable piston which contains a indicator mark 88 which could be a green neoprene 0-ring. Mounted onto the base of the movable piston is a plunger 69 which is of smaller diameter that of the outlet orifice from the sensor chamber. To help ensure that the device is tamper proof, the guide is screwed into the body with the aid of an industrial strength adhesive. The guide uses the 0-ring 209 to help ensure a fluid tight seal between itself and the body while the two grooves on the movable piston accommodate the two 0-rings 210 and 211. For those variations of this presentation where an additional shut-off mechanism is used, the pin 47 is removed and is replaced with a shut-off shaft and triggering mechanism whose axes are aligned, with the sensor chamber to a common datum. Under normal conditions, the shaft will locate the movable plug in the position as shown in figure 4. When the triggering mechanism holding the shut-off shaft releases, the movable plug is forced, by the shut-off shaft, to form a seal with the sealing means. To reset the triggering mechanism and to re-establish the fluid flow, the reset action of the movable piston will not only cause the pin to unseat the movable plug, but will travel sufficiently far to cause the shut-off shaft trigger to re-latch into its armed state. In figure 4, the fluid flow safety device is shown in the condition that it will be in when it is passing pressurized fluid at a rate below the maximum predetermined flow rate for that unit. The movable plug is near the base of the sensor chamber and the pressure in the pressure chamber forces the .movable piston into the position shown and the volume of the pressure chamber increases to its maximum. The upward travel of the movable piston is limited by the circlip 65 pressing against the angled stop 64 which has engaged the step in the guide hole's chamber walls at 208. If the pressure in the pressure chamber drops below a predetermined value, the tension in the spring 63 returns the movable piston to its rest position. For the horizontal version which incorporates an separate shut-off mechanism, which is not shown, the pin 47 is removed and a shaft mechanism is installed at point 199. This shaft mechanism is axially aligned with the axis of the sensor chamber and when in it is held open by the triggering system, positions the movable plug in the location as shown in this figure. When the triggering system has been released, the shaft mechanism forces the movable plug to form a seal with the sealing means thereby terminating the fluid flow. In figure 5, the fluid flow safety device is shown in the condition that it will be in when an emergency shut-off has occurred. The movable plug 56 has been forced onto the sealing means 50 at the outlet orifice end of the sensor chamber 49. As the pressure in the pressure chamber 52 has fallen below a predetermined valve, the spring 63 pressing on the spacer ring 204 which is located on the step in the guide hole's chamber walls at 207 forces the movable piston 60 to travel to the point where the angled stop 64 rests upon the vented plug 201. When the movable piston is in this position, the indicator mark 88 is not visible and the volume of the pressure chamber returns to its rest volume. In figure 6, an external force moves the movable piston to its reset position. The spring 63 is compressed and the reset pin prevents the movable plug from maintaining contact with the sealing means and the volume of the pressure chamber is decreased to, or near, its minimum. It should be noted that all of the devices described in the figures 1 to 6, can be used to test a pipe system for leaks. When the line has been pressurized and the fluid flow safety device has been reset, turn the cylinder valve off. Leave the system for about an hour and then check to see if the indicator mark is still visible. If it is not then a leak of some kind is present. In figure 7, the fluid flow safety device has been mounted into a modified form of the standard type of on/off valve which is currently marketed on LP gas cylinders. The body 101 has the standard features which include an attaching means 102 for connecting the valve body to the cylinder (not shown) which normally consist of a tapered thread. An inlet passageway 103 which leads to a safety valve mechanism 104 through a safety valve passageway 105, a primary valve seat 106, a primary valve 107, an outlet passageway 108 and an outlet aperture 109 for connection to further fluid transport mechanisms. An 80% decanting bleed tube 110 and bleed valve 111 are provided to aid the cylinder filling process. A valve mechanism including a handle 112, a spindle 113 and an attaching guide housing 114 are standard features. Many of the above mentioned features are covered by mandatory requirements and it was therefore essential that the current invention made no attempt to interfere with, or modify the operation or integrity of any of these features. The provision of a selective fluid flow sensor chamber 115, the sealing means 116, the tapered sensor chamber passageway 117, the rest position locating means 118 for the movable plug 119, the sensor chamber shield 120 which isolates the internal length of the sensor chamber from all other passageways and the axial alignment of these components provides an efficient, safe and consistent termination of the fluid flow from the open valve seat when the predetermined flow rate has been exceeded regardless of whatever fluid discharge may be occurring from any of the other orifices located in the body. The tapered sensor chamber passageway and the rest position of the movable plug make it virtually impossible to remove any gas from the cylinder when the cylinder is in the horizontal position. A very low discharge rate rolls the movable plug into contact with the sealing means and terminates the fluid flow. Domestic and commercial LP gas appliances are designed to operate on gas, not liquid fuel. The internal shape of the sensor chamber combined with the movable plug make it very hard to obtain a substantial flow of gas unless the cylinder is mounted in its correct orientation. This design has no critical tilt angles. Any deviation from the vertical in any direction will cause the maximum flow rate to diminish. Also, the positioning of the movable plug into its rest position by the aid of three fingers, provides a stable platform for the refilling process in that there is minimal pressure loss as the movable plug remains stationary during this procedure. With this design, when the on/off valve is in the off position, the pin 121 in the centre of the valve plug will not allow a seal to form between the movable plug and the sealing means. As the primary valve mechanism starts to open a small quantity of gas would be allowed to escape. This discharge is sufficient to pressurize the gas lines, or, if the main outlet is venting to the atmosphere, a further opening of the valve quickly causes the movable plug to terminate the fluid flow. According to the length of the pin, the termination should occur within the first twenty degrees of rotation of the spindle when venting to the atmosphere. Also, with this design, it is possible to unscrew and remove the primary valve mechanism from the body regardless of the contents of the gas cylinder. To reset the valve, it is a simple matter to turn the primary valve fully off, which opens the movable plug, and then slowly turn it back on to pressurize the line. In figure 8, a fluid flow safety shut-off mechanism is detailed. It is intended as a special upgrade for the cylinder type fluid flow safety device herein previously described. This unit is intended to be either a factory fit option or an upgrade kit for the after fit market. It provides an indicator and reset mechanism similar to those described in the figures 1 to 6. The attaching guide housing 122 screws into the body of the fluid flow safety device described in figure 7. A spindle 123 makes a threaded connection with the attaching guide housing and has a handle 124 located at the outer end and held in place with the aid of an indicator nut 125. Within the spindle is a spindle guide hole which contained a reset shaft 126. Screwed onto the outer end of the reset shaft is an extension 127 which includes an indicator mark 128. Between the two ends of the both the spindle and the reset shaft are two captured springs 129 and 130. These springs locate the reset shaft into a central position in relation to the spindle. Located within, and making a sealing and sliding contact with the attaching guide housing is a movable piston which contains within it a cylindrical chamber 132. Making a sliding and sealing contact within that cylindrical chamber is a reset plunger pin 133. Sealing the lower end of the cylindrical chamber is a valve plug 134. The orifice where the reset plunger pin passes through the valve plug is slightly oversized to allow pressurizing of the cylindrical chamber to occur. If the mechanism as detailed within figure 8 were installed in a valve body, it would show the condition of an emergency shut-off. The pressure in the pressure chamber has the movable piston touching the spindle, the reset plunger pin is touching the reset shaft, the spindle is in an open position and the indicator mark is not visible. In figure 9, a fluid flow safety shut-off mechanism is detailed in the reset position. The spindle 123 has been rotated to a near closed position and has moved the movable piston 131 to the lower end of the attaching guide housing 122. When the extension 127 has been depressed, the spring 130 compresses and the reset plunger pin extends itself through the valve plug 134. In this state, the reset plunger pin will deny seal to occur between the movable lug and the sealing means. In figure 10, a fluid flow safety shut-off mechanism is detailed in its armed position. The spindle 123 has been rotated within the attaching guide housing 122 to an open position. The pressure in the pressure chamber has forced the movable piston 131 into the attaching guide housing and into contact with the spindle. The pressure within the cylindrical chamber has forced the reset plunger pin 133 into its fully retracted position and has forced the reset shaft 126 to compress the spring 129 and, the extension 127 is positioned so that the indicator mark 128 is visible. It should be noted that this type of mechanism also is suitable the incorporation of a child proof lock which would deny access to the flammable fluids for those people not skilled in the art of such devices.

Claims: THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS: 1. A fluid flow safety device comprising; a body, having an inlet for connection to a fluid supply, a inlet passageway leading to a selective fluid flow sensor chamber, and locate at the outlet end of the said sensor chamber is a sealing means which encircle an outlet orifice and this outlet orifice is of smaller cross section than tha of the sensor chamber, said outlet orifice leading from the sensor chamber int a pressure chamber within the body; a movable piston which makes a sliding and sealing contac with the pressure chamber, and whose sliding movement from a rest positio increases or decreases the volume of the said pressure chamber; a passageway extending from the pressure chamber to a outlet aperture which is connectable to further fluid transport mechanisms; and a movable plug which is positioned within the selectiv fluid flow sensor chamber and can move between the inlet passageway end sto of the sensor chamber and the outlet orifice, and the movable plug is of greate diameter than the sensor chamber outlet orifice and is able to form a seal wit the sealing means. 2. A fluid flow safety device according to claim 1 wherein, th opposite end of the movable piston to that which is located within the bounds o the sliding and sealing contact of the pressure chamber, experiences the effect of atmospheric pressure. 3. A fluid flow safety device according to claim 1 or claim 2 wherein, the movable piston's central axis is substantially aligned with the central axis of the sensor chamber. 4. A fluid flow safety device according to any of the preceding claims wherein, the diameter of the movable plug in relation to the internal diameter of the sensor chamber allows a predetermined quantity of fluid to flow to the outlet orifice wherein an increase in the fluid flow above that predetermined quantity, draws the movable plug into a sealing contact with the sealing means at the outlet orifice. 5. A fluid flow safety device according to any of the preceding claims wherein, the sealing means located between the movable plug and the end of the sensor chamber is an 0-ring which encircles the outlet orifice. 6. A fluid flow safety device according to any of the preceding claims wherein, a plunger is incorporated into the base of the movable piston. 7. A fluid flow safety device according to any of the preceding claims wherein, the diameter of the plunger is of smaller diameter than the SUBSTITUTE SHEET (Role 26) diameter of the outlet orifice. 8. A fluid flow safety device according to any of the preceding claims wherein, when the movable piston is moved fully towards the sensor chamber, the plunger extends through the outlet orifice sufficiently far to deny a seal to occur between the movable plug and the sealing means at the outlet orifice. 9. A fluid flow safety device according to any of the preceding claims wherein, the movable piston is biased away from the sensor chamber. 10. A fluid flow safety device according to claim 9 wherein, the biasing means is a spring. 11. A fluid flow safety device according to claim 9 or claim 10 wherein, if there is no additional force acting upon the movable piston, the biasing means returns the movable piston to a rest position. 12. A fluid flow safety device according to claim 11 wherein, when the movable piston travels from its rest position to its extended position a biasing mechanism is compressed. 13. A fluid flow safety device according to claim 12 wherein, the biasing mechanism is a spring. 14. A fluid flow safety device according to any of the claims 10 to 13 wherein, the biasing means and the biasing mechanism is the one and the same spring. 15. A fluid flow safety device according to any of the preceding claims wherein, a sufficient build up of pressure in the pressure chamber moves the movable piston from the rest position to its fully extended position. 16. A fluid flow safety device according to any of the preceding claims wherein, the movable piston includes an extension which is of sufficient length to protrude proud of the body. 17. A fluid flow safety device according to any of the preceding claims wherein, an indicator mark is present on the movable piston extension and it is totally visible when the movable piston is in its fully extended position. 18. A fluid flow safety device according to any of the preceding claims wherein, the indicator mark is not visible when the movable piston is in its rest position 19. A fluid flow safety device according to any of the preceding claims wherein, an outlet passageway is incorporated into the movable piston. 20. A fluid flow safety device according to claim 19 wherein, the outlet aperture is incorporated into the extension from the movable piston which protrudes proud of the body. 21. A fluid flow safety device according to any of the preceding claims wherein, the inlet for connection to a fluid supply, the sensor chamber and the outlet aperture have their central axes aligned to a common datum. 22. A fluid flow safety device according to any of the claims 1 to 20 wherein, the axis of the inlet for connecting to a fluid supply and the axis of the outlet aperture are aligned to a common datum while the axis of the sensor chamber is at an angle to that datum. 23. A fluid flow safety device according to any of the claims 1 20 or wherein, the axis of the inlet for the connection to a fluid supply and the axis of the outlet aperture do not share a common datum. 24. A fluid flow safety device according to any of the preceding claims wherein, the axis of the inlet passageway and the axis of the inlet for connection to a fluid supply are not aligned to a common datum. 25. A fluid flow safety device according to any of the preceding claims wherein, a groove is present in the body in the internal chamber walls, adjacent to the movable piston, which can accommodate a compression clip ring. 26. A fluid flow safety device according to claim 25 wherein, the height of the groove in the chamber wall is sufficient to allow the movable piston to move to a point where the plunger can be inserted through the outlet orifice to disallow the seal between the sealing means and the movable plug. 27. A fluid flow safety device according to any of the preceding claims wherein, the groove in the chamber wall and the compression clip ring are replaced by a circular internal push-on fastener which locates itself onto the chamber wall. 28. A fluid flow safety device according to any of the claims 14 to 27 wherein, the single spring is located between two spacing ring stops and is pretensioned by a circlip positioned in a groove on the movable piston. 29. A fluid flow safety device according to claim 27 or claim 28 wherein, the movable piston is located in its rest position due to the positioning of the single spring and the two spacing ring stops between a step in the bore of the pressure chamber and a circular internal push-on fastener. 30. A fluid flow safety device according to any of the preceding claims wherein, an increase of fluid pressure in the pressure chamber above a predetermined value compresses the spring fully which limits the travel of the movable piston to its fully extended position. 31. A fluid flow safety device according to any of the preceding claims wherein, a bypass passageway leads from the inlet passageway and bypasses the sensor chamber outlet and connects to the outlet passageway. 32. A fluid flow safety device according to claim 31 wherein, a valve is installed within the bypass passageway. 33. A fluid flow safety device according to any of the precedin claims wherein, a filtering material is installed within the inlet passageway. 34. A fluid flow safety device according to any of the preceding claims wherein, a one way valve is installed in the outlet passageway. 35. A fluid flow safety device according to any of the preceding claims wherein, part of the bore of the sensor chamber passageway is tapered to a smaller diameter as it nears the sealing means. 36. A fluid flow safety device according to claim 35 wherein, the tapered sensor chamber passageway is a separate unit which can provide a location means for holding the 0-ring in place. 37. A fluid flow safety device according to any of the preceding claims wherein, the sensor chamber can be separated from the body. 38. A fluid flow safety device according to any of the preceding claims wherein, the sensor chamber and the inlet for connection to a fluid supply is separate from, and connectable to, the body. 39. A fluid flow safety device comprising; a body, having an inlet orifice and an inlet passageway leading to a selective fluid flow sensor chamber, and located at the outlet end of the said sensor chamber is a sealing means which encircles an outlet orifice and this outlet orifice is of smaller cross section than that of the sensor chamber, said outlet orifice leading from the sensor chamber into a pressure chamber within the body; a guide for the movable piston is located by the body to form part of the pressure chamber and has its axis is aligned to the axis of the outlet orifice; a movable piston which makes a sliding and sealing contact with the guide, and whose sliding movement from a rest position increases or decreases the volume of the pressure chamber; a passageway extending from the pressure chamber to an outlet aperture which is connectable to further fluid transport mechanisms; and a movable plug which is positioned within the selective fluid flow sensor chamber and can move between the inlet passageway end stop of the sensor chamber and the outlet orifice, and the movable plug is of greater diameter than the sensor chamber outlet orifice and is able to form a seal with the sealing means. 40. A fluid flow safety device according to claim 39 wherein, an inlet assembly with a fluid passageway and a mating connection forms a fluid tight seal with the body inlet orifice and further provides a connection to a fluid supply source. 41. A fluid flow safety device according to claim 39 or claim 40 wherein, the opposite end of the movable piston to that which is located within the bounds of the sliding and sealing contact inside the pressure chamber, experiences the effect of atmospheric pressure. 42. A fluid flow safety device according to any of the claims 39 to 41 wherein, the movable piston's central axis is substantially aligned with the central axis of the sensor chamber. 43. A fluid flow safety device according to any of the claims 39 to 42 wherein, the diameter of the movable plug in relation to the internal diameter of the selective fluid flow sensor chamber allows a predetermined quantity of fluid to flow to the outlet orifice wherein an increase in the fluid flow above that predetermined quantity, draws the movable plug into sealing contact with the sealing means at the outlet orifice. 44. A fluid flow safety device according to any of the claims 39 or claim 43 wherein, the sealing means located between the movable plug and the end of the sensor chamber is an 0-ring which encircles the outlet orifice. 45. A fluid flow safety device according to any of the claims 39 to 44 wherein, a plunger is incorporated into the base of the movable piston. 46. A fluid flow safety device according to any of the claims 39 to 45 wherein, the diameter of the plunger is of smaller diameter than the diameter of the outlet orifice. 47. A fluid flow safety device according to any of the claims 39 to 46 wherein, when the movable piston is moved fully towards the sensor chamber, the plunger extends through the outlet orifice sufficiently far to deny a seal to occur between the movable plug and the sealing means at the outlet orifice. 48. A fluid flow safety device according to any of the claims 39 to 47 wherein, the movable piston is biased away from the sensor chamber. 49. A fluid flow safety device according to claim 48 wherein, the biasing means is a spring. 50. A fluid flow safety device according to claim 48 or claim 49 wherein, if there is no additional force acting upon the movable piston, the biasing means returns the movable piston to a rest position. 51. A fluid flow safety device according to claim 50 wherein, when the movable piston travels from its rest position to its fully extended position a biasing mechanism is compressed. 52. A fluid flow safety device according to claim 51 wherein, the biasing mechanism is a spring. 53. A fluid flow safety device according to any of the claims 48 to 52 wherein, the biasing means and the biasing mechanism is the one and the same spring. 54. A fluid flow safety device according to any of the claims 39 to 52 wherein, a sufficient build up of pressure in the pressure chamber moves the movable piston from the rest position to its fully extended position. 55. A fluid flow safety device according to any of the claims 39 to 54 wherein, the movable piston includes an extension which is of sufficient length to allow that extension to protrude proud of the guide. 56. A fluid flow safety device according to any of the claims 39 to 55 wherein, an indicator mark is present on the movable piston extension which is totally visible when the movable position is in its fully extended position. 57. A fluid flow safety device according to any of the claims 39 to 56 wherein, the indicator mark is not visible when the movable piston is in its rest position. 58. A fluid flow safety device according to any of the claims 52 to 57 wherein, the single spring is located between two spacer rings and is pretensioned by a circlip positioned in a groove on the movable piston. 59. A fluid flow safety device according to any of the claims 39 to 58 wherein, the movable piston is located in its rest position due to the positioning of the single spring and the two spacer rings between a step in the bore of the guide and a vented plug located onto the base of the guide. 60. A fluid flow safety device according to any of the claims 39 to 59 wherein, an additional step is incorporated into the internal bore of the guide such that an increase of fluid pressure in the pressure chamber above a predetermined value compresses the spring and the spring spacer adjacent to the circlip on the movable piston engages with the additional step which limits the outward travel of the movable piston. 61. A fluid flow safety device according to any of the claims 39 to 60 wherein, the outlet orifice and the sealing means of the sensor chamber are removable from the body. 62. A fluid flow safety device according to claim 61 wherein, the removable outlet orifice and the sealing means are held in position by the vented plug in the base of the guide. 63. A fluid flow safety device according to any of the claims 39 to 62 wherein, the bore of the sensor chamber passageway is tapered to a smaller diameter as it nears the sealing means. 64. A fluid flow safety device according to claim 63 wherein, the tapered sensor chamber passageway is a separate unit and can provide a location means for holding the 0-ring in place. 65. A fluid flow safety device according to any of the claims 39 to 64 wherein, the sensor chamber can be separated from the body. 66. A fluid flow safety device according to any of the claims 40 to 65 wherein, a filtering material is installed within the inlet assembly fluid passageway. 67. A fluid flow safety device according to any of the claims 39 to 66 wherein, a one way valve is installed in the outlet passageway. 68. A fluid flow safety device according to any of the claims 39 to 67 wherein, the body has a mating relationship with the inlet assembly such that the body can be rotated around the axis of the inlet assembly. 69. A fluid flow safety device according to claim 68 wherein, when the body has been rotated into a fully inverted position, the movable plug forms a seal with the sealing means of the sensor chamber. 70. A fluid flow safety device according to any of the claims 39 to 69 wherein, a bypass passageway leads from the inlet passageway and bypasses the sensor chamber outlet. 71. A fluid flow safety device according to any of the claims 39 to 70 wherein, a valve is installed within the bypass passageway. 72. A fluid flow safety device comprising; an inlet assembly with a fluid passageway for connection to a fluid supply, a body having an inlet passageway leading to a selective fluid flow sensor chamber, and located at the outlet end of the of the said sensor chamber is a sealing means which encircles an outlet orifice and this outlet orifice is of smaller cross section than that of the sensor chamber, said outlet orifice leading from the sensor chamber to a pressure chamber within the body; a movable piston which makes a sliding and sealing contact within the pressure chamber, and whose sliding movement from a rest position increases or decreases the volume of the pressure chamber; a passageway extending from the pressure chamber to an outlet aperture which is connectable to further fluid transport mechanisms; a movable plug which is positioned within the selective fluid flow sensor chamber and is located between the inlet passageway and the outlet orifice, and the movable plug is of greater diameter than the sensor chamber outlet orifice; and a separate shut-off mechanism to provide an independent control for terminating the fluid flow. 73. A fluid flow safety device according to claim 72 wherein, the diameter of the movable plug in relation to the internal diameter of the sensor chamber allows a predetermined quantity of fluid to flow to the outlet orifice wherein an increase in the fluid flow above that predetermined quantity, draws the movable plug into a sealing contact with the sealing means at the outlet orifice. 74. A fluid flow safety device according to claim 72 or claim 73 wherein, the sealing means located between the movable plug and the end of the sensor chamber is an 0-ring which encircles the outlet orifice. 75. A fluid flow safety device according to any of the claims 72 to 74 wherein, the opposite end of the movable piston to that which is located within the bounds of the sliding and sealing contact of the pressure chamber, experiences the effect of atmospheric pressure. 76. A fluid flow safety device according to any of the claims 72 to 75 wherein, the movable piston's central axis is substantially aligned with the central axis of the sensor chamber. 77. A fluid flow safety device according to any of the claims 72 to 76 wherein, the separate shut-off mechanism can also initiate the fluid flow. 78. A fluid flow safety device according to any of the claims 72 to 77 wherein, the separate shut-off mechanism is located upstream of the sensor chamber. 79. A fluid flow safety device according to any of the claims 72 to 78 wherein, the separate shut-off mechanism is biased towards the closed position. 80. A fluid flow safety device according to any of the claims 72 to 79 wherein, the separate shut-off mechanism which is biased towards the closed position is held in the open state by a triggering system. 81. A fluid flow safety device according to any of the claims 72 to 80 wherein, the triggering system is responsive to vibration movement. 82. A fluid flow safety device according to any of the claims 72 to 80 wherein, the triggering system is responsive to heat. 83. A fluid flow safety device according to any of the claims 72 to 80 wherein, the triggering system is responsive to an electrical impulse. 84. A fluid flow safety device according to any of the claims 72 to 80 wherein, the triggering system incorporates a sensing chamber which will activate the trigger in responsive to a change in the fluid pressure. 85. A fluid flow safety device according to any of the claims 72 to 84 wherein, the separate shut-off mechanism causes the movable plug in the sensor chamber to form a seal with the sealing means which encircles the outlet orifice . 86. A fluid flow safety device according to any of the claims 72 to 77 wherein, the separate shut-off mechanism is located downstream of the sensor chamber outlet orifice. 87. A fluid flow safety device according to claim 86 wherein, the separate shut-off mechanism valve seat encircles the outlet side passageway of the sensor chamber outlet orifice. 88. A fluid flow safety device according to claim 86 or claim 87 wherein, the separate shut-off mechanism valve plug is located such that it forms a fluid seal with the separate shut-off mechanism valve seat. 89. A fluid flow safety device according to claim 88 wherein, the separate shut-off mechanism valve plug is incorporated onto the base of the movable piston. 90. A fluid flow safety device according to any of the claims 86 to 89 wherein, the movable piston is propelled into its closed position by the action of a spindle mechanism. 91. A fluid flow safety device according to any of the claims 86 to 90 wherein, the axes of the separate shut-off mechanism valve plug, spindle, valve seat and sensor chamber share a common datum. * 92. A fluid flow safety device according to any of the claims 86 to 91 wherein, the movable piston is biased from its rest position by a sufficient build up of pressure in the pressure chamber. 93. A fluid flow safety device according the claim 92 wherein, when the spindle has been retracted to its open position and there is a sufficient build up of pressure in the pressure chamber, the movable piston moves the separate shut-off mechanism valve plug to an open state. 94. A fluid flow safety device according to any of the claims 72 to 93 wherein, the separate shut-off mechanism valve plug includes a protrusion pin which extends through an oversized orifice from the base of the valve plug. 95. A fluid flow safety device according to any of the claims 72 to 94 wherein, the protrusion pin extending from the base of the valve plug is of smaller diameter than that of the outlet orifice. 96. A fluid flow safety device according to any of the claims 72 to 95 wherein, as the separate shut-off mechanism valve plug approaches its closed position, the protrusion pin denies a seal to occur between the movable plug and the sealing means. 97. A fluid flow safety device according to any of the claims 90 to 93 wherein, within the movable piston is a cylindrical chamber whose axis is aligned with that of the movable piston. 98. A fluid flow safety device according to claim 97 wherein, one end of the reset plunger pin makes a sliding, sealing contact within the cylindrical chamber while the other end is located within an oversized orifice in the centre of the separate shut-off mechanism valve plug. 99. A fluid flow safety device according to claim 97 or claim 98 wherein, the reset plunger pin within the cylindrical chamber is biased to a retracted position. 100. A fluid flow safety device according to any of the claims 97 to 99 wherein, the end of the reset plunger pin which makes a sliding and sealing contact within the cylindrical chamber experiences the effect of atmospheric pressure. 101. A fluid flow safety device according to claim 99 or claim 100 wherein, the biasing means for the reset plunger pin is a sufficient build up of pressure in the cylindrical chamber which moves the reset plunger to a retracted state. 102. A fluid flow safety device according to any of the claims 97 to 101 wherein, the spindle has a central guide hole present which extends longitudinally through its central axis. 103. A fluid flow safety device according to any of the claims 90 to 102 wherein, a reset shaft is located within the spindle's guide hole. 104. A fluid flow safety device according to any of the claims 90 to 103 wherein, the reset shaft is biased towards a rest position. 105. A fluid flow safety device according to claim 104 wherein, the biasing means is a spring. 106. A fluid flow safety device according to any of the claims 97 to 105 wherein, when the reset shaft is moved to its reset position it engages with the reset plunger pin and extends it through the separate shut-off mechanism valve seat to its reset position. 107. A fluid flow safety device according to claim 106 wherein, as the separate shut-off mechanism valve plug approaches its closed position, the reset plunger pin denies a seal to occur between the movable plug and the sealing means. 108. A fluid flow safety device according to any of the claims 103 to 107 wherein, the reset shaft has a second biasing means which locates it into a rest position. 109. A fluid flow safety device according to claim 108 wherein, the second biasing means is a spring. 110. A fluid flow safety device according to any of the claims 103 to 109 wherein, the reset shaft includes an extension which protrudes past the outside end of the spindle. Ill. A fluid flow safety device according to any of the claims 103 to 110 wherein, an indicator mark is present on the reset shaft extension which is only visible when the reset shaft is in its fully extended position. 112. A fluid flow safety device according to claim 110 or claim 111 wherein, when there is sufficient pressure built up around the oversized orifice of the plug, yalve the reset plunger pin moves -to its fully retracted state and compresses the second biasing means which causes the indicator mark on the reset shaft extension to become visible. 113. A fluid flow safety device according to any of the claims 72 to 112 wherein, a bypass passageway leads from the inlet passageway and bypasses the sensor chamber outlet and connects to the outlet passageway. 114. A fluid flow safety device according to claim 113 wherein, a valve is installed within the bypass passageway. 115. A fluid flow safety device according to claim 114 wherein, the valve is a solenoid valve. 116. A fluid flow safety device according to any of the claims 72 to 115 wherein, a filtering material is installed within the inlet passageway. 117. A fluid flow safety device according to any of the claims 72 to 116 wherein, a one way valve is installed in the outlet passageway. 118. A fluid flow safety device according to any of the claims 72 to 117 wherein, the bore of the sensor chamber passageway is tapered to a smaller diameter as it nears the sealing means. 119. A fluid flow safety device according to claim 118 wherein, the tapered sensor chamber passageway is a separate unit which can provide a location means for holding the 0-ring in place. 120. A fluid flow safety device according to any of the preceding claims wherein, the sensor chamber and the sealing means can be separated from the body. 121. A fluid flow safety device comprising; a body having an inlet end for connection to a fluid supply and an outlet end for connecting to further fluid transport mechanisms, an inlet passageway leading to a valve orifice passageway which leads to a primary valve seat and primary valve pressure chamber which connects via the outlet passageway to the outlet end; a primary valve mechanism is located within the primary valve pressure chamber such that it can form a fluid tight seal between the inlet and the outlet passageways by engaging with the primary valve seat; a selective fluid flow sensor chamber positioned between the inlet end and the primary valve seat and located at the outlet end of the said sensor chamber is a sealing means which encircles an outlet orifice and this outlet orifice is of smaller cross section than that of the sensor chamber said outlet orifice leading from the sensor chamber to the valve orifice; a sensor chamber shield which encircles the sensor chamber by forming, defining and separating the internal length of the sensor chamber passageway from that of the inlet or any other passageway; a movable plug which is positioned within the fluid flow sensor chamber and can move between the inlet passageway end of the sensor chamber and the outlet orifice, and the movable plug is of greater diameter than the sensor chamber outlet orifice and is able to form a seal with the sealing means. 122. A fluid flow safety device according to claim 121 wherein, the movable plug in its open position is located in the centre of the inlet end of the sensor chamber. 123. A fluid flow safety device according to claim 122 wherein, three or more detents or fingers supported by the sensor chamber shield provide the open position for the movable plug. 124. A fluid flow safety device according to any of the claims 121 to 123 wherein, a safety valve passageway extends from the inlet passageway to a safety valve mechanism which has been designed to vent to the atmosphere that fluid .from the safety valve passageway should the pressure in that passageway raise above a predetermined value. 125. A fluid flow safety device according to any of the claims 121 to 124 wherein, the safety valve passageway encircles the sensor chamber shield. 126. A fluid flow safety device according to any of the claims 121 to 125 wherein, the diameter of the movable plug in relation to the internal diameter of the sensor chamber allows a predetermined quantity of fluid to flow to the outlet orifice wherein an increase in the fluid flow above that predetermined quantity, draws the movable plug into a sealing contact with the sealing means at the outlet orifice. 127. A fluid flow safety device according to any of the claims 121 to 126 wherein, the responsiveness of the closing ability of the movable plug remains unaltered regardless of any discharge from the safety valve. 128. A fluid flow safety device according to any of the claims 121 to 127 wherein, the sealing means located between the movable plug and the end of the sensor chamber is an 0-ring which encircles the outlet orifice. 129. A fluid flow safety device according to any of the claims 121 to 128 wherein, part of the bore of the sensor chamber passageway is tapered to a smaller diameter as it nears the sealing means. 130. A fluid flow safety device according to claim 129 wherein, the tapered sensor chamber passageway is a separate unit which can provide a location means for holding the 0-ring in place. 131. A fluid flow safety device according to any of the claims 121 to 130 wherein, he opposite end of the primary valve to that which is located within the bounds of the sliding and sealing contact of the primary valve pressure chamber, experiences the effect of atmospheric pressure. 132. A fluid flow safety device according to any of the claims 121 to 131 wherein, the primary valve's central axis is substantially aligned with the central axis of the sensor chamber. 133. A fluid flow safety device according to any of the claims 121 to 132 wherein, a separate shut-off mechanism is located upstream of the sensor chamber. 134. A fluid flow safety device according to any of the claims 121 to 133 wherein, the separate shut-off mechanism can also initiate the fluid flow. 135. A fluid flow safety device according to any of the claims 121 to 134 wherein, the separate shut-off mechanism is biased towards the closed position. 136. A fluid flow safety device according to any of the claims 121 to 135 wherein, the separate shut-off mechanism which is biased towards the closed position is held in the open state by a triggering system. 137. A fluid flow safety device according to any of the claims 121 to 136 wherein, the triggering system is responsive to vibration movement. 138. A fluid flow safety device according to any of the claims 121 to 137 wherein, the triggering system is responsive to an external signal. 139. A fluid flow safety device according to any of the claims 121 to 138 wherein, the triggering system incorporates a sensing chamber which will activate the trigger in responsive to a change in the fluid pressure. 140. A fluid flow safety device according to any of the claims 121 to 139 wherein, the separate shut-off mechanism causes the movable plug in the sensor chamber to form a seal with the sealing means which encircles the outlet orifice. 141. A fluid flow safety device according to any of the claims 121 to 140 wherein, the primary valve seat encircles the outlet passageway side of the sensor chamber outlet orifice. 142. A fluid flow safety device according to claim 141 wherein, the primary valve is propelled into its closed position by the action of a spindle mechanism. 143. A fluid flow safety device according to any of the claims 121 to 142 wherein, the axes of the primary valve, spindle, primary valve seat and sensor chamber share a common datum. 144. A fluid flow safety device according to any of the claims 121 to 143 wherein, when the spindle has been retracted to an open position, it moves the primary valve to an open state. 145. A fluid flow safety device according to any of the claims 121 to 143 wherein, when the spindle has been retracted to its open position and there is a sufficient build up of pressure in the pressure chamber, the pressure moves the primary valve to an open state. 146. A fluid flow safety device according to any of the claims 121 to 145 wherein, the primary valve includes a protrusion pin which extends from the base of the primary valve. 147. A fluid flow safety device according to any of the claims 1321 to 146 wherein, the protrusion pin extending from the base of the primary valve is of smaller diameter than that of the outlet orifice. 148. A fluid flow safety device according to any of the claims 121 to 147 wherein, as the primary valve approaches its closed position, the protrusion pin denies a seal to occur between the movable plug and the sealing means. 149. A fluid flow safety device according to any of the claims 121 to 148 wherein, within the primary valve is a cylindrical chamber whose axis is aligned with that of the movable piston. 150. A fluid flow safety device according to claim 149 wherein, within the cylindrical chamber is a reset pin, one end of which makes a sealing and sliding contact with the cylindrical chamber while the other end is located an oversized orifice in the centre of the primary valve. 151. A fluid flow safety device according to claim 149 or claim 150 wherein, when the reset pin has been moved to the bottom of the cylindrical chamber, the other end of the reset pin protrudes proud of the base of the primary valve. 152. A fluid flow safety device according to any of the claims 149 to 151 wherein, as the primary valve approaches or is at its closed position, the reset pin can be moved to the bottom of the cylindrical chamber which allows the other end of the reset pin to deny a seal to occur between the movable plug and the sealing means. 153. A fluid flow safety device according to any of the claims 121 to 153 wherein, the selective fluid flow sensor chamber and/or the sensor chamber shield are removable from the body. 154. A fluid flow safety device according to any of the claims 121 to 153 wherein, when the pressure in the pressure chamber is above a predetermined valve, an external indicator registers the pressure increase. 155. A fluid flow safety device according to any of the previous claims wherein, the movable plug is a metal ball. 156. A fluid flow safety device according to any of the previous claims wherein, the movable ball is biased towards the open position. 157. A fluid flow safety device according to claim 156 wherein, the biasing means is a magnetic force. 158. A fluid flow safety device according to any of the previous claims wherein, when the movable piston is in the rest position, the free flow of fluid from the inlet to the outlet passageway is severely restricted. 159. A fluid flow safety device according to any of the previous claims wherein, the internal passageways include a flashback arrester. 160. A fluid flow safety device according to any of the claims 1 to 38 and claims 121 to 159 wherein, the body is mounted vertically. 161. A fluid flow safety device according to any of the claims 39 to 120 and claim 159 wherein, the body is mounted in a horizontal orientation. 162. A fluid flow safety shut-off mechanism comprising; an attaching guide housing which is connectable with a fluid flow safety device body, said attaching guide housing containing a central guide hole and a mating connection for a spindle mechanism; a movable piston which makes a sealing and sliding contact within the central guide hole in the attaching guide housing, said movable piston containing a cylindrical chamber and a valve plug; a reset plunger pin, one end of which makes a sliding, sealing contact within the cylindrical chamber while the other end is located within an oversized orifice in the centre of the valve plug; a spindle mechanism which makes a mating connection with the attaching guide housing and which, when rotated towards its closed position, urges the movable piston from the attaching guide housing and the said spindle contains a central guide hole which extends longitudinally through its central axis; a handle which combines with the spindle to transmit the rotational movement to the spindle. 163. A fluid flow safety shut-off mechanism according to claim 162 wherein, a reset shaft is located within the spindle's guide hole. 164. A fluid flow safety shut-off mechanism according to claim 162 and claim 163 wherein, the reset shaft is biased towards a rest position. 165. A fluid flow safety shut-off mechanism according to any of the claims 162 to 164 wherein, the biasing means is a spring. 166. A fluid flow safety shut-off mechanism according to any of the claims 162 to 165 wherein, when the reset shaft is moved to its reset position, it engages with the reset plunger pin and extends it through the valve plug to its reset position. 167. A fluid flow safety shut-off mechanism according to claim 164 wherein, when it is installed into a matching fluid flow safety device as previously described, and as the valve plug approaches or is at its closed position and the reset shaft is depressed, the reset plunger pin denies a seal to occur between the movable plug and the sealing means. 168. A fluid flow safety shut-off mechanism according to any of the claims 162 to 167 wherein, the reset shaft has a second biasing means which locates it into a rest position. 169. A fluid flow safety shut-off mechanism according to claim 168 wherein, the biasing means is a spring. 170. A fluid flow safety shut-off mechanism according to any of the claims 162 to 169 wherein, the reset shaft includes an extension which protrudes past the outside end of the spindle. 171. A fluid flow safety shut-off mechanism according to any of the claims 162 to 170 wherein, an indicator mark is present on the reset shaft extension which is only visible when the reset shaft is in its fully extended position. 172. A fluid flow safety shut-off mechanism according to claim 170 or claim 171 wherein, when there is a sufficient build up of pressure around the oversized orifice of the valve plug, the reset plunger pin moves to its fully retracted state and compresses the second biasing means which causes the indicator mark on the reset shaft extension to become visible. 173. A fluid flow safety shut-off mechanism according to any of the claims 121 to 172 wherein, an inter-lock is included on the primary valve mechanism which requires a specific form of manual manipulation to establish a fluid flow after the primary valve has been turned off thus providing "child safe" protection. 174. A fluid flow safety device, substantially as hereinbefore described with reference to the accompanying drawings.

Inventors: ESPLIN TREVOR THOMAS, MORRISON JEAN, MORRISON WALTER, ESPLIN, TREVOR, THOMAS, MORRISON, JEAN, MORRISON, WALTER
Applicants: ESPLIN TREVOR THOMAS, MORRISON JEAN, MORRISON WALTER, ESPLIN, TREVOR, THOMAS, MORRISON, JEAN, MORRISON, WALTER
Application year: 1994
Main classification: F16K17
IPC codes: F16K17, F17C13